Direct injection internal combustion engines rely on high pressure fuel systems that include a low pressure fuel sub-system. For example, some high pressure fuel systems may include at least a high pressure pump and a low pressure pump which provides fuel of a lower pressure to the high pressure pump. If the low pressure fuel sub-system, including the low pressure pump, is unable to provide sufficient fuel flow and fuel pressure to the high pressure pump, degradation or damage to the high pressure pump or other fuel system components may result. One approach for addressing this issue is to monitor the low pressure fuel sub-system via a fuel pressure sensor.
The inventors of the present disclosure have recognized some issues with the above approach. For example, these fuel pressure sensors may be prohibitively expensive and may be subject to the durability of the fuel pressure sensor. Furthermore, fuel pressure sensors may be limited by their response and/or range sensing characteristics. In order to address these and other issues, the inventors herein have provided an engine system and a method for its operation.
In one embodiment, the engine system includes an internal combustion engine; a fuel passage for supplying fuel to the internal combustion engine; a fuel pump arranged along the fuel passage; a fuel filter arranged along the fuel passage downstream of the fuel pump; a fuel pressure switch arranged along the fuel passage downstream of the fuel filter; and a control system. The fuel pressure switch is configured to switch to a high pressure state in response to a higher fuel pressure within the fuel passage downstream of the fuel filter and switch to a low pressure state in response to a lower fuel pressure within the fuel passage downstream of the fuel filter. The control system is configured to indicate a clogging of the fuel filter based on a period of time that the fuel pressure switch remains in the low pressure state. In some embodiments, the control system may respond to an indicated clogging of the fuel system by limiting one or more of fuel pressure, fuel flow rate, and vehicle speed. Further, the control system may respond to an indicated clogging of the fuel system by issuing a notification to the vehicle operator or service personnel.
This approach when utilized in conjunction with a fuel pressure switch offers a less expensive and more robust alternative to the previous fuel pressure sensor. Furthermore, the fuel pressure switch may not be limited to the extent that the fuel pressure sensor would be with respect to its response and/or range sensing characteristics. By limiting the flow rate and/or the pressure at which fuel is delivered to the internal combustion engine during conditions when the low pressure fuel sub-system is unable to provide sufficient fuel pressure and/or flow, degradation and/or damage to the fuel system, including the high pressure pump, may be reduced or eliminated.